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Concrete Technology (41-60)

Updated: Apr 9, 2020

41. For concreting of heavily reinforced sections without vibration, the workability

of concrete expressed as compacting factor should be above 0.92


42. Maximum quantity of water needed per 50kg of cement for M 15 grade of concrete is 32 liters


43.In case of hand mixing of concrete, the extra cement to be added is 10%


44. For walls, columns and vertical faces of all structural members, the form work is generally removed after 24 to 48 hours


45. The individual variation between test strength of sample should not be more

than ± 15% of average


46. One of the criteria for the effective width of flange of T-beam is

distance between points of zero moments in the beam


47. For a cantilever of effective depth of 0.5 m, the maximum span to satisfy vertical deflection limit is 3.5 m


48. For a simply supported beam of span 15 m, the minimum effective depth to satisfy the vertical deflection limits should be 750 mm


49. For a continuous slab of 3 m x 3.5 m size,the minimum overall depth of slab to

satisfy vertical deflection limits is 75 mm


50. According to IS : 456-1978, the fiexural strength of concrete is directly proportional to square root of compressive strength


51. According to IS : 456-1978, the column orthe strut is the member whose effective length is greater than 3 times the least lateral dimension


52. According to IS : 456- 1978, minimum slendemess ratio for a short column is

less than 12


53. Lap length in compression shall not be less than 24 Φ


54. The minimum cover in a slab should neither be less than the diameter of bar nor less than 15 mm


55. For a longitudinal reinforcing bar in a column, the minimum cover shall neither be less than the diameter of bar nor less than 40 mm


56. The ratio of the diameter of reinforcing bars and the slab thickness is 1/8


57.According to IS: 456-1978, the maximum reinforcement in a column is 6 %


58. The percentage of reinforcement in case of slabs, when high strength deformed bars are used is not less than 0.12


59.Minimum cross sectional area of longitudinal reinforcement in a column is 0.8%.,Spacing of longitudinal bars measured along the periphery of

column should not exceed 300 mm ,Reinforcing bars in a column should

not be less than 12 mm in diameter.


60.Higher Vee-Bee time shows lower workability

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